Sex- and age-based differences in the delivery and outcomes of critical care

Background: Previous studies have suggested that a patient's sex may influence the provision and outcomes of critical care. Our objective was to determine whether sex and age are associated with differences in admission practices, processes of care and clinical outcomes for critically ill patients. Methods: We used a retrospective cohort of 466 792 patients, including 24 778 critically ill patients, admitted consecutively to adult hospitals in Ontario between Jan. 1, 2001, and Dec. 31, 2002. We measured associations between sex and age and admission to the intensive care unit (ICU); use of mechanical ventilation, dialysis or pulmonary artery catheterization; length of stay in the ICU and hospital; and death in the ICU, hospital and 1 year after admission. Results: Of the 466 792 patients admitted to hospital, more were women than men (57.0% v. 43.0% for all admissions, p < 0.001; 50.1% v. 49.9% for nonobstetric admissions, p < 0.001). However, fewer women than men were admitted to ICUs (39.9% v. 60.1%, p < 0.001); this difference was most pronounced among older patients ( age >= 50 years). After adjustment for admission diagnoses and comorbidities, older women were less likely than older men to receive care in an ICU setting ( odds ratio [ OR] 0.68, 95% confidence interval [CI] 0.66-0.71). After adjustment for illness severity, older women were also less likely than older men to receive mechanical ventilation ( OR 0.91, 95% CI 0.81-0.97) or pulmonary artery catheterization ( OR 0.80, 95% CI 0.73-0.88). Despite older men and women having similar severity of illness on ICU admission, women received ICU care for a slightly shorter duration yet had a longer length of stay in hospital ( mean 18.3 v. 16.9 days; p=0.006). After adjustment for differences in comorbidities, source of admission, ICU admission diagnosis and illness severity, older women had a slightly greater risk of death in the ICU ( hazard ratio 1.20, 95% CI 1.10-1.31) and in hospital ( hazard ratio 1.08, 95% CI 1.00-1.16) than did older men. Interpretation: Among patients 50 years or older, women appear less likely than men to be admitted to an ICU and to receive selected life-supporting treatments and more likely than men to die after critical illness. Differences in presentation of critical illness, decision-making or unmeasured confounding factors may contribute to these findings.